Fcc catalyst prepared by a process involving more than one silica material

ABSTRACT

Process for the preparation of a catalyst and a catalyst comprising more than one silica is provided herein. Thus, in one embodiment, the invention provides a particulate FCC catalyst comprising about 5 to about 60 wt % one or more zeolites, about 10 to about 45 wt % quasicrystalline boehmite (QCB), about 0 to about 35 wt % microcrystalline boehmite (MCB), greater than about 0 to about 15 wt % silica from sodium stabilized colloidal silica, greater than about 0 to about 30 wt % silica from ammonia stabilized or lower sodium colloidal silica, and the balance clay and the process for making the same. This process results in attrition resistant catalysts with good performance.

FIELD OF THE INVENTION

The present invention pertains to a catalyst composition and its use ina process for the cracking or conversion of a feed comprised ofhydrocarbons, such as, for example, those obtained from the processingof crude petroleum, with better physical properties and performance.

BACKGROUND

A common challenge in the design and production of heterogeneouscatalysts is to find a good compromise between the effectiveness and/oraccessibility of the active sites and the effectiveness of theimmobilising matrix in giving the catalyst particles sufficient physicalstrength, i.e. attrition resistance.

The preparation of attrition resistant catalysts is disclosed in severalprior art documents. U.S. Pat. No. 4,086,187 discloses a process for thepreparation of an attrition resistant catalyst by spray-drying anaqueous slurry prepared by mixing (i) a faujasite zeolite with a sodiumcontent of less than 5 wt % with (ii) kaolin, (iii) peptisedpseudoboehmite, and (iv) ammonium polysilicate. The attrition resistantcatalysts according to U.S. Pat. No. 4,206,085 are prepared byspray-drying a slurry prepared by mixing two types of acidifiedpseudoboehmite, zeolite, alumina, clay, and either ammonium polysilicateor silica sol.

WO 02/098563 discloses a process for the preparation of an FCC catalysthaving both a high attrition resistance and a high accessibility. Thecatalyst is prepared by slurrying zeolite, clay, and boehmite, feedingthe slurry to a shaping apparatus, and shaping the mixture to formparticles, characterised in that just before the shaping step themixture is destabilised. This destabilisation is achieved by, e.g.,temperature increase, pH increase, pH decrease, or addition ofgel-inducing agents such as salts, phosphates, sulphates, and(partially) gelled silica. Before destabilisation, any peptisablecompounds present in the slurry must have been well peptised.

WO 06/067154 describes an FCC catalyst, its preparation and its use. Itdiscloses a process for the preparation of an FCC catalyst having both ahigh attrition resistance and a high accessibility. The catalyst isprepared by slurrying a clay, zeolite, a sodium-free silica source,quasi-crystalline boehmite, and micro-crystalline boehmite, providedthat the slurry does not comprise peptised quasi-crystalline boehmite,b) adding a monovalent acid to the slurry, c) adjusting the pH of theslurry to a value above 3, and d) shaping the slurry to form particles.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to an FCC catalyst meant to be employed inthe process for cracking, a hydrocarbon feed over a particular catalystcomposition to produce conversion product hydrocarbon compounds of lowermolecular weight than feed hydrocarbons, e.g., product comprising a highgasoline fraction. A unique feature of the invention is the use of morethan one silica source.

Thus, in one embodiment, provided is a particulate FCC catalystcomprising about 5 to about 60 wt % one or more zeolites, about 10 toabout 45 wt % quasicrystalline boehmite (QCB), about 0 to about 35 wt %microcrystalline boehmite (MCB), greater than about 0 to about 15 wt %silica from sodium stabilized colloidal silica, greater than about 0 toabout 30 wt % silica from ammonia stabilized or lower sodium colloidalsilica, and the balance clay.

In another embodiment, provided is a process for manufacturing an FCCcatalyst, wherein the process comprises:

-   -   (a) Adding, clay, boehmite, sodium stabilized colloidal silica        to form a slurry;    -   (b) Digesting the slurry with a monoprotic acid to a pH of less        than 4;    -   (c) Adding one or more zeolites to the slurry;    -   (d) Adding the ammonia stabilized or lower sodium colloidal        silica at any time during or after steps (a)-(c) but before step        (e);    -   (e) Mixing the slurry and then destabilizing the slurry by        raising the pH to above 4.0;    -   (f) Shaping and collecting the resulting FCC Catalyst.

The resulting catalyst shows improved benefits over that known in theart. It is evident from the physical properties (ABD and attrition) thatthe catalysts of the present invention showed similar attributes as tothe catalysts known in the art. However, each of the catalysts showedperformance advantages, particularly on bottoms or coke.

In a still further embodiment, provided is a process for cracking apetroleum fraction feedstock said process comprising the steps of:

-   -   a) providing an FCC catalyst composition comprising about 5 to        about 60 wt % one or more zeolites, about 10 to about 45 wt %        quasicrystalline boehmite, about 0 to about 35 wt %        microcrystalline boehmite, greater than about 0 to about 15 wt %        silica from sodium stabilized colloidal silica, greater than        about 0 to about 30 wt % silica from ammonia stabilized or lower        sodium colloidal silica, and the balance clay;    -   b) contacting the FCC catalyst with said petroleum fraction        feedstock at a temperature in the range of from 400 to 650° C.,        with a dwell time in the range of from 0.5 to 12 seconds.

These and still other embodiments, advantages and features of thepresent invention shall become further apparent from the followingdetailed description, including the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise indicated, weight percent (______ wt %) as used hereinis the dry base weight percent of the specified form of the substance,based upon the total dry base weight of the product for which thespecified substance or form of substance is a constituent or component.It should further be understood that, when describing steps orcomponents or elements as being preferred in some manner herein, theyare preferred as of the initial date of this disclosure, and that suchpreference(s) could of course vary depending upon a given circumstanceor future development in the art.

General Procedure

The first step of the process of manufacturing the improved catalyst isto mix clay sources, with sodium stabilized colloidal silica, and one ormore alumina (boehmite) sources. As will be discussed below, one canoptionally add a second silica source of ammonia stabilized or lowersodium colloidal silica to this slurry or at a later step. The clay,zeolite, QCB, MCB, sodium stabilized colloidal silica, and optionalother components can be slurried by adding them to water as dry solids.Alternatively, slurries containing the individual materials are mixed toform the slurry. It is also possible to add some of the materials asslurries, and others as dry solids. Optionally, other components may beadded, such as aluminium chlorohydrol, aluminium nitrate, Al₂O₃,Al(OH)₃, anionic clays (e.g. hydrotalcite), smectites, sepiolite, bariumtitanate, calcium titanate, calcium-silicates, magnesium-silicates,magnesium titanate, mixed metal oxides, layered hydroxy salts,additional zeolites, magnesium oxide, bases or salts, and/or metaladditives such as compounds containing an alkaline earth metal (forinstance Mg, Ca, and Ba), a Group IIIA transition metal, a Group IVAtransition metal (e.g. Ti, Zr), a Group VA transition metal (e.g. V,Nb), a Group VIA transition metal (e.g. Cr, Mo, W), a Group VIIAtransition metal (e.g. Mn), a Group VIIIA transition metal (e.g. Fe, Co,Ni, Ru, Rh, Pd, Pt), a Group IB transition metal (e.g. Cu), a Group IIBtransition metal (e.g. Zn), a lanthanide (e.g. La, Ce), or mixturesthereof. Any order of addition of these compounds may be used. It isalso possible to combine these compounds all at the same time.

The term “boehmite” is used in the industry to describe alumina hydrateswhich exhibit X-ray diffraction (XRD) patterns close to that ofaluminium oxide-hydroxide [AlO(OH)]. Further, the term boehmite isgenerally used to describe a wide range of alumina hydrates whichcontain different amounts of water of hydration, have different surfaceareas, pore volumes, specific densities, and exhibit different thermalcharacteristics upon thermal treatment. Yet their XRD patterns, althoughthey exhibit the characteristic boehmite [AlO(OH)] peaks, usually varyin their widths and can also shift in their location. The sharpness ofthe XRD peaks and their location has been used to indicate the degree ofcrystallinity, crystal size, and amount of imperfections.

Broadly, there are two categories of boehmite aluminas:quasi-crystalline boehmites (QCBs) and micro-crystalline boehmites(MCBs). In the state of the art, quasi-crystalline boehmites are alsoreferred to as pseudo-boehmites and gelatinous boehmites. Usually, theseQCBs have higher surface areas, larger pores and pore volumes, and lowerspecific densities than MCBs. They disperse easily in water or acids,have smaller crystal sizes than MCBs, and contain a larger number ofwater molecules of hydration. The extent of hydration of QCB can have awide range of values, for example from about 1.4 up to about 2 moles ofwater per mole of Al, intercalated usually orderly or otherwise betweenthe octahedral layers. Some typical commercially available QCBs arePural®, Catapal®, and Versal® products.

Microcrystalline boehmites are distinguished from the QCBs by their highdegree of crystallinity, relatively large crystal size, very low surfaceareas, and high densities. Contrary to QCBs, MCBs show XRD patterns withhigher peak intensities and very narrow half-widths. This is due totheir relatively small number of intercalated water molecules, largecrystal sizes, the higher degree of crystallization of the bulkmaterial, and the smaller amount of crystal imperfections. Typically,the number of water molecules intercalated can vary in the range fromabout 1 up to about 1.4 per mole of Al.

The slurry preferably comprises about 1 to about 50 wt %, morepreferably about 10 to about 35 wt %, of non-peptised QCB based on thefinal catalyst. The slurry also comprises about 0 to about 50 wt %, morepreferably about 0 to about 35 wt % of MCB based on the final catalyst.

The clay is preferred to have a low sodium content, or to besodium-free. Suitable clays include kaolin, bentonite, saponite,sepiolite, attapulgite, laponite, hectorite, English clay, anionic clayssuch as hydrotalcite, and heat- or chemically treated clays such asmeta-kaolin. The slurry preferably comprises about 5 to about 70 wt %,more preferably about 10 to about 60 wt %, and most preferably about 10to about 50 wt % of clay based on the final catalyst.

In a next step, a monovalent acid is added to the suspension, causingdigestion. Both organic and inorganic monovalent acids can be used, or amixture thereof. Examples of suitable monovalent acids are formic acid,acetic acid, propionic acid, nitric acid, and hydrochloric acid. Theacid is added to the slurry in an amount sufficient to obtain a pH lowerthan 7, more preferably between 1 and 4.

In the next step, one or more zeolites are added. The zeolites used inthe process according to the present invention preferably have a lowsodium content (less than 1.5 wt % Na₂O), or are sodium-free. Suitablezeolites to be used include zeolites such as Y-zeolites—including HY,USY, dealuminated Y, RE-Y, and RE-USY—zeolite beta, ZSM-5,phosphorus-activated ZSM-5, ion-exchanged ZSM-5, MCM-22, and MCM-36,metal-exchanged zeolites, ITQs, SAPOs, ALPOs, and mixtures thereof. Theslurry preferably comprises 5 to 60 wt % of one or more zeolite based onthe final catalyst.

As will be discussed below, a second silica source may be added to theslurry at any point prior if the second silica source is ammoniastabilized or lower sodium colloidal silica.

The above slurry is then passed through a high sheer mixer where it isdestabilized by increasing the pH. The pH of the slurry is subsequentlyadjusted to a value above 3, more preferably above 3.5, even morepreferably above 4. The pH of the slurry is preferably not higher than7, because slurries with a higher pH can be difficult to handle. The pHcan be adjusted by adding a base (e.g. NaOH or NH₄OH) to the slurry. Thetime period between the pH adjustment and shaping step d) preferably is30 minutes or less, more preferably less than 5 minutes, and mostpreferably less than 3 minutes. At this step, the solids content of theslurry preferably is about 10 to about 45 wt %, more preferably about 15to about 40 wt %, and most preferably about 25 to about 35 wt %.

The slurry is then shaped. Suitable shaping methods includespray-drying, pulse drying, pelletising, extrusion (optionally combinedwith kneading), beading, or any other conventional shaping method usedin the catalyst and absorbent fields or combinations thereof. Apreferred shaping method is spray-drying. If the catalyst is shaped byspray-drying, the inlet temperature of the spray-dryer preferably rangesfrom 300 to 600° C. and the outlet temperature preferably ranges from105 to 200° C.

Silica Sources

A unique feature of the present invention is the use of at least twosources of silica within the catalyst particle. The total amount ofsilica added is greater than 1.0%. It is preferred that the total silicais greater than about 5.0% and it is most preferred that the totalamount of silica is greater than about 10.0%. Further, it is preferredthat the ratio of the first silica source to the second silica source isfrom about 1:1 to about 1:10.

The first source of silica is typically a low sodium silica source andis added to the initial slurry. Examples of such silica sources include,but are not limited to potassium silicate, sodium silicate, lithiumsilicate, calcium silicate, magnesium silicate, barium silicate,strontium silicate, zinc silicate, phosphorus silicate, and bariumsilicate. Examples of suitable organic silicates are silicones(polyorganosiloxanes such as polymethylphenylsiloxane andpolydimethylsiloxane) and other compounds containing Si—O—C—O—Sistructures, and precursors thereof such as methyl chlorosilane, dimethylchlorosilane, trimethyl chlorosilane, and mixtures thereof. Preferredlow sodium silica sources are sodium stabilized colloidal silicas. Theslurry further comprises greater than 0 to about 15 wt % and morepreferably greater than about 0.5 to about 10 wt % of silica from thelow sodium silicon source based on the weight of the final catalyst andmost preferred greater than about 1 wt % to 8 wt %.

The second silica source is typically an ammonia stabilized colloidalsilica or a lower sodium-stabilized silica that has sodium content lowerthan that in the first silica source. Generally, ammonia stabilized orlower sodium colloidal silica has pH about 7-11 with the presence ofammonia as charge stabilizer. More commonly, pH of ammonia stabilizedcolloidal is about 8-10.5. Ammonia stabilized silica may also have verylow sodium or is essentially sodium free. Suitable silicon sources to beadded as a second silica source include (poly)silicic acid, ammoniumsilicate, sodium-free silicon sources, and organic silicon or mixturesthereof. This second addition of silica is added in an amount of greaterthan about 0 to 30 wt %, preferably greater than about 1 wt % to about25 wt % and most preferably about 5 to about 20% based on the weight ofthe final catalyst.

The Resulting Catalyst

The catalyst is generally an FCC catalyst comprising about 5 to about60% one or more zeolites, about 10 to about 45 wt % quasicrystallineboehmite, about 0 to about 25 wt % microcrystalline boehmite, greaterthan about 0 wt % to about 15 wt % silica from sodium stabilizedcolloidal silica, greater than about 0 wt % to about 30 wt % silica fromammonia stabilized or lower sodium colloidal silica, and the balanceclay.

These catalysts can be used as FCC catalysts or FCC additives inhydroprocessing catalysts, alkylation catalysts, reforming catalysts,gas-to-liquid conversion catalysts, coal conversion catalysts, hydrogenmanufacturing catalysts, and automotive catalysts. The process of theinvention is particularly applicable to Fluid Catalytic Cracking (FCC).In the FCC process, the details of which are generally known, thecatalyst, which is generally present as a fine particulate comprisingover 90 wt % of the particles having diameters in the range of about 5to about 300 microns. In the reactor portion, a hydrocarbon feedstock isgasified and directed upward through a reaction zone, such that theparticulate catalyst is entrained and fluidized in the hydrocarbonfeedstock stream. The hot catalyst, which is coming from theregenerator, reacts with the hydrocarbon feed which is vaporized andcracked by the catalyst. Typically temperatures in the reactor are400-650 C and the pressure can be under reduced, atmospheric orsuperatmospheric pressure, usually about atmospheric to about 5atmospheres. The catalytic process can be fixed bed, moving bed, orfluidized bed, and the hydrocarbon flow may be either concurrent orcountercurrent to the catalyst flow. The process of the invention isalso suitable for TCC (Thermofor catalytic cracking) or DCC.

EXAMPLES

Prior to any lab testing the catalyst must be deactivated to simulatecatalyst in a refinery unit, this is typically done with steam. Thesesamples were deactivated either by cyclic deactivation with Ni/V whichconsists of cracking, stripping and regeneration steps in the presenceof steam or with 100% steam at higher temperatures, which areindustrially accepted deactivation methods for FCC catalysts. Thedeactivation step is known in the art, and is necessary to catalyticactivity. In commercial FCC setting, deactivation occurs shortly aftercatalyst introduction, and does not need to be carried out as a separatestep.

Example 1

Four separate examples were made using the techniques described herein.Each separate example was compared to a base case of using a singlesilica source. The amount of each silica varied for each of theexamples, as detailed below in the tables. It is evident from thephysical properties (ABD and attrition) data shown below that all thecatalysts of the present invention showed similar attributes as to thebase catalysts. However, each of the catalysts showed performanceadvantages, particularly on bottoms or coke.

The examples were subjected to a Fluid Microactivity test, orFluidized-bed Simulation Test (FST) or Advanced Cracking Evaluation(ACE). ACE is a test known and generally accepted in the art forascertaining the FCC cracking activity of a catalyst. In ACE, the testis conducted with a series of four catalyst-to-feed ratios (CTO) whichare obtained by varying the mass of feed injected to the reactor, whileusing the same amount of catalyst for all runs. The testing apparatussimulates the cracking of a known amount of a hydrocarbon feedstock ofknown amount and compositional characteristics. This small scale testingunit is a once through unit and operated approximately as in ASTM5154-10.

The attrition resistance of the catalysts was measured using a methodsubstantially based on ASTM 5757 Standard Test Method for Determinationof Attrition and Abrasion of Powdered Catalysts by Air Jets, the resultsfrom which indicate that the more attrition resistant the catalyst is,the lower the resulting attrition index value observed when testing amaterial using the above-referenced method.

Example 1-A

Catalyst Description Comparative 1 Catalyst 1 Low soditun colloidalsilica 20.0 5.0 NH4-colloidal silica 0.0 15.0 Properties Comparative 1Catalyst 1 ABD 0.69 0.74 Attrition 1.52 0.83 Testing Comparative 1Catalyst 1 430° F. + Conversion, wt % 75.05 74.93 Catalyst-to-Oil, wt/wt5.00 5.00 Coke 4.18 4.06 % coke reduction 3% 650° F. + 9.22 8.90 %bottoms upgrading 4%

Example 1-B

Catalyst Description Comparative 2 Catalyst 2 Low sodium colloidalsilica 20.0 5.0 NH4-colloidal silica 0.0 15.0 Properties Comparative 2Catalyst 2 ABD 0.71 0.7 Attrition 1.14 1.04 Testing Comparative 2Catalyst 2 430° F. + Conversion, wt % 74.66 75.04 Catalyst-to-Oil, wt/wt5.00 5.00 Coke 4.18 4.10 % coke reduction 2% 650° F. + 9.35 9.18 %bottoms upgrading 2%

Example 1-C

Catalyst Description Comparative 3 Catalyst 3 Catalyst 4 Low sodiumcolloidal silica 13.0 5.0 5.0 NH4-colloidal silica 0.0 8.0 8.0Properties Comparative 3 Catalyst 3 Catalyst 4 ABD 0.68 0.67 0.67Attrition 1.27 1.36 1.30 Testing Comparative 3 Catalyst 3 Catalyst 4430° F. + Conversion, wt % 74.52 76.20 75.75 Catalyst-to-Oil, wt/wt 5.005.00 5.00 Coke 4.27 3.77 3.95 % coke reduction 12% 8% 650° F. + 9.309.22 9.31 % bottoms upgrading 1% 0%

1. An FCC catalyst composition comprising about 5 to about 60 wt % oneor more zeolites, about 10 to about 45 wt % quasicrystalline boehmite,about 0 to about 35 wt % microcrystalline boehmite, greater than 0 wt %to about 15 wt % silica from sodium stabilized colloidal silica, greaterthan 0 wt % to about 30 wt % silica from ammonia stabilized or lowersodium colloidal silica, and the balance clay.
 2. The FCC Catalyst ofclaim 1 with greater than 0.5 wt % to about 10 wt % silica from sodiumstabilized colloidal silica.
 3. The FCC Catalyst of claim 2 with greaterthan 1 wt % to about 8 wt % silica from sodium stabilized colloidalsilica.
 4. The FCC Catalyst of claim 1 with greater than 1 wt % to about25 wt % silica from ammonia stabilized or lower sodium colloidal silica.5. The FCC Catalyst of claim 4 with greater than 5 wt % to about 20 wt %silica from ammonia stabilized or lower sodium colloidal silica.
 6. Aprocess for manufacturing an FCC catalysts comprising: a. Adding, clay,boehmite, sodium stabilized colloidal silica to form a slurry; b.Digesting the slurry with a monoprotic acid to a pH of less than 4; c.Adding one or more zeolites to the slurry; d. Adding an ammoniastabilized or lower sodium colloidal silica at any time during or aftersteps (a)-(c) but before step (e); e. Mixing the slurry and thendestabilizing the slurry by raising the pH to above 4.0; f. Shaping andcollecting the resulting FCC Catalyst.
 7. The process of claim 6 furthercomprising adding about 5 to about 60 wt % one or more zeolites.
 8. Theprocess of claims 6 further comprising adding greater than 0 to about 15wt % silica from sodium stabilized basic colloidal silica.
 9. Theprocess of claims 6 further comprising adding greater than 0.5 wt % toabout 10 wt % silica from sodium stabilized colloidal silica.
 10. Theprocess of claim 6 further comprising adding greater than 0 to about 30wt % ammonia stabilized or lower sodium colloidal silica.
 11. Theprocess of claim 6 further comprising adding greater than 1 wt % toabout 25 wt % silica from ammonia stabilized or lower sodium colloidalsilica.
 12. The process of claim 6 further comprising adding greaterthan 5 wt % to about 20 wt % silica from ammonia stabilized or lowersodium colloidal silica.
 13. A catalyst made from the process of claims6 comprising about 5 to about 60 wt % one or more zeolites, about 10 toabout 45 wt % quasicrystalline boehmite, about 0 to about 35 wt %microcrystalline boehmite, greater than 0 to about 15 wt % silica fromsodium stabilized basic colloidal silica, greater than 0 to about 30 wt% silica from ammonia stabilized or lower sodium colloidal silica, andthe balance clay.
 14. A process for producing more liquid componentsfrom a hydrocarbon feedstock, said process comprising the steps of: a.providing an FCC catalyst composition of about 5 to about 60 wt % one ormore zeolites, about 10 to about 45 wt % quasicrystalline boehmite,about 0 to about 35 wt % microcrystalline boehmite, greater than 0 toabout 15 wt % silica from sodium stabilized basic colloidal silica,greater than 0 to about 30 wt % silica from ammonia stabilized or lowersodium colloidal silica, and the balance clay; b. contacting the FCCparticulate catalyst composition with the hydrocarbon feedstock, at oneor more temperatures in the range of about 400 to about 650° C., with adwell time in the range of about 0.5 to about 12 seconds; such thatpropylene is formed with a conversion efficiency in the range of about 4to about 20 wt %, based upon the weight of the hydrocarbon feedstock.